Sampling of the 30 m deep chlorophyll a, however, was too short (19 months) to provide a seasonal signal and, although significantly correlated to the surface values (r = 0.5∗∗; n = 81) chlorophyll a concentrations at 30 m were generally higher. Over a shorter period (April 2002–April 2004), Torréton et al. (2010) report on two relative maxima, one in January and the other, between April and June at Station M33 for the 3–20 m water column.